Final answer:
A black hole is logically impossible in a data flow diagram (DFD) because it does not produce any output, which contradicts the fundamental nature of a process in a DFD.
Step-by-step explanation:
A black hole is logically impossible in a data flow diagram (DFD) because a process must act on input, shown by an incoming data flow, and produce output, represented by an outgoing data flow. A black hole, which does not allow anything to escape its gravitational pull, does not fit this model.
In a DFD, all processes have inputs and outputs, and they are interconnected by data flows. Each process takes the input, performs some operation, and produces an output. This is why a black hole cannot exist in a DFD as it does not produce an output.
For example, in a DFD representing a banking system, a process could be withdrawing money from an account. The input would be the account number and the amount to withdraw, and the output would be the updated account balance. A black hole, on the other hand, does not produce any output, which contradicts the fundamental nature of a process in a DFD.